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[/] [System09/] [rev_86/] [rtl/] [System09_Xilinx_ML506/] [my_system09.vhd] - Blame information for rev 138

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1 59 davidgb 
--===========================================================================----
2 
--
3 
--  S Y N T H E Z I A B L E    System09 - SOC.
4 
--
5 
--  www.OpenCores.Org - September 2003
6 
--  This core adheres to the GNU public license
7 
--
8 
-- File name      : System09.vhd
9 
--
10 
-- Purpose        : Top level file for 6809 compatible system on a chip
11 
--                  Designed with Xilinx XC3S200 Spartan 3 FPGA.
12 
--                  Implemented With Digilent Xilinx Starter FPGA board,
13 
--
14 
-- Dependencies   : ieee.Std_Logic_1164
15 
--                  ieee.std_logic_unsigned
16 
--                  ieee.std_logic_arith
17 
--                  ieee.numeric_std
18 
--
19 
-- Uses           : mon_rom   (sys09bug_rom4k_b16.vhd) Monitor ROM
20 
--                  cpu09     (cpu09.vhd)              CPU core
21 
--                  dat_ram   (datram.vhd)             Dynamic Address Translation
22 
--                  acia_6850 (acia_6850.vhd)          ACIA (UART)
23 
--                            (acia_rx.vhd)
24 
--                            (acia_tx.vhd)
25 
--                  keyboard  (keyboard.vhd)           PS/2 Keyboard
26 
--                            (ps2_keyboard.vhd)
27 
--                            (keymap_rom)
28 
--                  vdu8      (vdu8.vhd)                          Video Display Unit
29 
--                            (char_rom2K_b16.vhd)
30 
--                            (ram2k_b16.vhd)
31 
--                  seven_segment (SevenSegment.vhd)   Seven Segment Display
32 
--
33 
-- Author         : John E. Kent
34 
--                  dilbert57@opencores.org
35 
--
36 
--===========================================================================----
37 
--
38 
-- Revision History:
39 
--===========================================================================--
40 
-- Version 0.1 - 20 March 2003
41 
-- Version 0.2 - 30 March 2003
42 
-- Version 0.3 - 29 April 2003
43 
-- Version 0.4 - 29 June 2003
44 
--
45 
-- Version 0.5 - 19 July 2003
46 
-- prints out "Hello World"
47 
--
48 
-- Version 0.6 - 5 September 2003
49 
-- Runs SBUG
50 
--
51 
-- Version 1.0- 6 Sep 2003 - John Kent
52 
-- Inverted sys_clk
53 
-- Initial release to Open Cores
54 
--
55 
-- Version 1.1 - 17 Jan 2004 - John Kent
56 
-- Updated miniUart.
57 
--
58 
-- Version 1.2 - 25 Jan 2004 - John Kent
59 
-- removed signals "test_alu" and "test_cc"
60 
-- Trap hardware re-instated.
61 
--
62 
-- Version 1.3 - 11 Feb 2004 - John Kent
63 
-- Designed forked off to produce System09_VDU
64 
-- Added VDU component
65 
--      VDU runs at 25MHz and divides the clock by 2 for the CPU
66 
-- UART Runs at 57.6 Kbps
67 
--
68 
-- Version 2.0 - 2 September 2004 - John Kent
69 
-- ported to Digilent Xilinx Spartan3 starter board
70 
--      removed Compaact Flash and Trap Logic.
71 
-- Replaced SBUG with KBug9s
72 
--
73 
-- Version 2.1 - 21 November 2006 - John Kent
74 
-- Replaced KBug9s with Sys09bug 1.0
75 
-- Inverted bottom nybble of DAT register outputs
76 
-- Changed ROM & I/O decoding to be compatible with SWTPc
77 
-- Upped the serial baud rate to 115.2 KBd
78 
-- added multiple global clock buffers
79 
-- (Uart would not operate correctly)
80 
--
81 
-- Version 2.2 - 22 December 2006 - John Kent
82 
-- Increased CPU clock from 12.5MHz to 25 MHz.
83 
-- Removed some of the global clock buffers
84 
-- Added LED output register
85 
-- Changed address decoding to 4K Blocks
86 
--
87 
-- Version 2.3 - 1 June 2007 - John Kent
88 
-- Updated VDU & ACIA
89 
-- Changed decoding for Sys09Bug
90 
--
91 
-- Version 2.4 - 31 January 2008 - John Kent
92 
--      ACIA does not appear to work.
93 
-- Made RAM OE and WE strobes synchonous to sys_clk
94 
--
95 
--===========================================================================--
96 
library ieee;
97 
   use ieee.std_logic_1164.all;
98 
   use IEEE.STD_LOGIC_ARITH.ALL;
99 
   use IEEE.STD_LOGIC_UNSIGNED.ALL;
100 
   use ieee.numeric_std.all;
101 
 
102 
entity my_system09 is
103 
  port(
104 
    sys_clk     : in  Std_Logic;  -- System Clock input
105 
         rst_sw    : in  Std_logic;  -- Master Reset input (active high)
106 
         nmi_sw      : in  Std_logic;
107 
 
108 
    -- Memory Interface signals
109 
    ram_addr    : out Std_Logic_Vector(17 downto 0);
110 
    ram_wen     : out Std_Logic;
111 
    ram_oen     : out Std_Logic;
112 
 
113 
    ram1_cen    : out Std_Logic;
114 
         ram1_ubn    : out Std_Logic;
115 
         ram1_lbn    : out Std_Logic;
116 
    ram1_data   : inout Std_Logic_Vector(15 downto 0);
117 
 
118 
    ram2_cen    : out Std_Logic;
119 
         ram2_ubn    : out Std_Logic;
120 
         ram2_lbn    : out Std_Logic;
121 
    ram2_data   : inout Std_Logic_Vector(15 downto 0);
122 
 
123 
         -- PS/2 Keyboard
124 
         ps2c        : inout Std_logic;
125 
         ps2d        : inout Std_Logic;
126 
 
127 
         -- ACIA Interface
128 
    rxd         : in  Std_Logic;
129 
         txd         : out Std_Logic;
130 
 
131 
         -- CRTC output signals
132 
         vs          : out Std_Logic;
133 
    hs          : out Std_Logic;
134 
    blue        : out std_logic;
135 
    green       : out std_logic;
136 
    red         : out std_logic;
137 
 
138 
         -- LEDS & Switches
139 
         leds        : out std_logic_vector(7 downto 0);
140 
         switches    : in  std_logic_vector(7 downto 0);
141 
 
142 
         -- seven segment display
143 
         segments    : out std_logic_vector(7 downto 0);
144 
         digits      : out std_logic_vector(3 downto 0)
145 
         );
146 
end my_system09;
147 
 
148 
-------------------------------------------------------------------------------
149 
-- Architecture for System09
150 
-------------------------------------------------------------------------------
151 
architecture my_computer of my_system09 is
152 
  -----------------------------------------------------------------------------
153 
  -- constants
154 
  -----------------------------------------------------------------------------
155 
  constant SYS_Clock_Frequency  : integer := 50000000;  -- FPGA System Clock
156 
  constant VGA_Clock_Frequency  : integer := 25000000;  -- VGA Pixel Clock
157 
  constant CPU_Clock_Frequency  : integer := 25000000;  -- CPU Clock
158 
  constant BAUD_Rate            : integer := 57600;       -- Baud Rate
159 
  constant ACIA_Clock_Frequency : integer := BAUD_Rate * 16;
160 
 
161 
  type hold_state_type is ( hold_release_state, hold_request_state );
162 
 
163 
  -----------------------------------------------------------------------------
164 
  -- Signals
165 
  -----------------------------------------------------------------------------
166 
  -- BOOT ROM
167 
  signal rom_cs        : Std_logic;
168 
  signal rom_data_out  : Std_Logic_Vector(7 downto 0);
169 
 
170 
  -- FLEX9 RAM
171 
  signal flex_cs       : Std_logic;
172 
  signal flex_data_out : Std_Logic_Vector(7 downto 0);
173 
 
174 
  -- ACIA Interface signals
175 
  signal acia_clk      : std_logic;
176 
  signal acia_data_out : Std_Logic_Vector(7 downto 0);
177 
  signal acia_cs       : Std_Logic;
178 
  signal acia_irq      : Std_Logic;
179 
  signal acia_rxd      : Std_Logic;
180 
  signal acia_txd      : Std_Logic;
181 
  signal acia_dcd_n    : Std_Logic;
182 
--  signal acia_rts_n    : Std_Logic;
183 
  signal acia_cts_n    : Std_Logic;
184 
 
185 
  -- keyboard port
186 
  signal keyboard_data_out : std_logic_vector(7 downto 0);
187 
  signal keyboard_cs       : std_logic;
188 
  signal keyboard_irq      : std_logic;
189 
 
190 
  -- LEDs
191 
  signal leds_data_out : std_logic_vector(7 downto 0);
192 
  signal leds_cs       : std_logic;
193 
 
194 
  -- RAM
195 
  signal ram_cs       : std_logic; -- memory chip select
196 
  signal ram_data_out : std_logic_vector(7 downto 0);
197 
  signal ram1_ce      : std_logic;
198 
  signal ram1_ub      : std_logic;
199 
  signal ram1_lb      : std_logic;
200 
  signal ram2_ce      : std_logic;
201 
  signal ram2_ub      : std_logic;
202 
  signal ram2_lb      : std_logic;
203 
  signal ram_we       : std_logic;
204 
  signal ram_oe       : std_logic;
205 
 
206 
  -- CPU Interface signals
207 
  signal cpu_reset    : Std_Logic;
208 
  signal cpu_clk      : Std_Logic;
209 
  signal cpu_rw       : std_logic;
210 
  signal cpu_vma      : std_logic;
211 
  signal cpu_halt     : std_logic;
212 
  signal cpu_hold     : std_logic;
213 
  signal cpu_firq     : std_logic;
214 
  signal cpu_irq      : std_logic;
215 
  signal cpu_nmi      : std_logic;
216 
  signal cpu_addr     : std_logic_vector(15 downto 0);
217 
  signal cpu_data_in  : std_logic_vector(7 downto 0);
218 
  signal cpu_data_out : std_logic_vector(7 downto 0);
219 
 
220 
  -- Dynamic Address Translation
221 
  signal dat_cs       : std_logic;
222 
  signal dat_addr     : std_logic_vector(7 downto 0);
223 
 
224 
  -- Video Display Unit
225 
  signal vdu_cs       : std_logic;
226 
  signal vdu_data_out : std_logic_vector(7 downto 0);
227 
  signal vga_clk      : std_logic;
228 
 
229 
  -- 7 Segment Display
230 
  signal seg_cs       : std_logic;
231 
  signal seg_data_out : std_logic_vector(7 downto 0);
232 
 
233 
  -- System Clock Prescaler
234 
  signal clk_count    : std_logic;
235 
 
236 
-----------------------------------------------------------------
237 
--
238 
-- CPU09 CPU core
239 
--
240 
-----------------------------------------------------------------
241 
 
242 
component cpu09
243 
  port (
244 
         clk      :     in  std_logic;
245 
    rst      : in  std_logic;
246 
    rw       :  out std_logic;          -- Asynchronous memory interface
247 
    vma      :  out std_logic;
248 
    address  : out std_logic_vector(15 downto 0);
249 
    data_in  : in        std_logic_vector(7 downto 0);
250 
         data_out : out std_logic_vector(7 downto 0);
251 
         halt     : in  std_logic;
252 
         hold     : in  std_logic;
253 
         irq      : in  std_logic;
254 
         nmi      : in  std_logic;
255 
         firq     : in  std_logic
256 
  );
257 
end component;
258 
 
259 
 
260 
----------------------------------------
261 
--
262 
-- 4KByte Block RAM Monitor ROM
263 
--
264 
----------------------------------------
265 
component mon_rom
266 
  Port (
267 
    clk      : in  std_logic;
268 
    rst      : in  std_logic;
269 
    cs       : in  std_logic;
270 
    rw       : in  std_logic;
271 
    addr     : in  std_logic_vector (11 downto 0);
272 
    rdata    : out std_logic_vector (7 downto 0);
273 
    wdata    : in  std_logic_vector (7 downto 0)
274 
    );
275 
end component;
276 
 
277 
----------------------------------------
278 
--
279 
-- 8KBytes Block RAM for FLEX9
280 
-- $C000 - $DFFF
281 
--
282 
----------------------------------------
283 
component flex_ram
284 
  Port (
285 
    clk      : in  std_logic;
286 
    rst      : in  std_logic;
287 
    cs       : in  std_logic;
288 
    rw       : in  std_logic;
289 
    addr     : in  std_logic_vector (12 downto 0);
290 
    rdata    : out std_logic_vector (7 downto 0);
291 
    wdata    : in  std_logic_vector (7 downto 0)
292 
    );
293 
end component;
294 
 
295 
----------------------------------------
296 
--
297 
-- Dynamic Address Translation Registers
298 
--
299 
----------------------------------------
300 
component dat_ram
301 
  port (
302 
    clk      : in  std_logic;
303 
         rst      : in  std_logic;
304 
         cs       : in  std_logic;
305 
         rw       : in  std_logic;
306 
         addr_lo  : in  std_logic_vector(3 downto 0);
307 
         addr_hi  : in  std_logic_vector(3 downto 0);
308 
    data_in  : in  std_logic_vector(7 downto 0);
309 
         data_out : out std_logic_vector(7 downto 0)
310 
  );
311 
end component;
312 
 
313 
-----------------------------------------------------------------
314 
--
315 
-- 6850 ACIA
316 
--
317 
-----------------------------------------------------------------
318 
 
319 
component ACIA_6850
320 
  port (
321 
    clk      : in  Std_Logic;  -- System Clock
322 
    rst      : in  Std_Logic;  -- Reset input (active high)
323 
    cs       : in  Std_Logic;  -- ACIA Chip Select
324 
    rw       : in  Std_Logic;  -- Read / Not Write
325 
    irq      : out Std_Logic;  -- Interrupt
326 
    Addr     : in  Std_Logic;  -- Register Select
327 
    DataIn   : in  Std_Logic_Vector(7 downto 0); -- Data Bus In
328 
    DataOut  : out Std_Logic_Vector(7 downto 0); -- Data Bus Out
329 
    RxC      : in  Std_Logic;  -- Receive Baud Clock
330 
    TxC      : in  Std_Logic;  -- Transmit Baud Clock
331 
    RxD      : in  Std_Logic;  -- Receive Data
332 
    TxD      : out Std_Logic;  -- Transmit Data
333 
         DCD_n    : in  Std_Logic;  -- Data Carrier Detect
334 
    CTS_n    : in  Std_Logic;  -- Clear To Send
335 
    RTS_n    : out Std_Logic   -- Request To send
336 
  );
337 
end component;
338 
 
339 
-----------------------------------------------------------------
340 
--
341 
-- ACIA Clock divider
342 
--
343 
-----------------------------------------------------------------
344 
 
345 
component ACIA_Clock
346 
  generic (
347 
     SYS_Clock_Frequency  : integer :=  SYS_Clock_Frequency;
348 
          ACIA_Clock_Frequency : integer := ACIA_Clock_Frequency
349 
  );
350 
  port (
351 
     clk      : in  Std_Logic;  -- System Clock Input
352 
          ACIA_clk : out Std_logic   -- ACIA Clock output
353 
  );
354 
end component;
355 
 
356 
 
357 
----------------------------------------
358 
--
359 
-- PS/2 Keyboard
360 
--
361 
----------------------------------------
362 
 
363 
component keyboard
364 
  generic(
365 
  KBD_Clock_Frequency : integer := CPU_Clock_Frequency
366 
  );
367 
  port(
368 
  clk             : in    std_logic;
369 
  rst             : in    std_logic;
370 
  cs              : in    std_logic;
371 
  rw              : in    std_logic;
372 
  addr            : in    std_logic;
373 
  data_in         : in    std_logic_vector(7 downto 0);
374 
  data_out        : out   std_logic_vector(7 downto 0);
375 
  irq             : out   std_logic;
376 
  kbd_clk         : inout std_logic;
377 
  kbd_data        : inout std_logic
378 
  );
379 
end component;
380 
 
381 
----------------------------------------
382 
--
383 
-- Video Display Unit.
384 
--
385 
----------------------------------------
386 
component vdu8
387 
      generic(
388 
        VDU_CLOCK_FREQUENCY    : integer := CPU_Clock_Frequency; -- HZ
389 
        VGA_CLOCK_FREQUENCY    : integer := VGA_Clock_Frequency; -- HZ
390 
             VGA_HOR_CHARS          : integer := 80; -- CHARACTERS
391 
             VGA_VER_CHARS          : integer := 25; -- CHARACTERS
392 
             VGA_PIXELS_PER_CHAR    : integer := 8;  -- PIXELS
393 
             VGA_LINES_PER_CHAR     : integer := 16; -- LINES
394 
             VGA_HOR_BACK_PORCH     : integer := 40; -- PIXELS
395 
             VGA_HOR_SYNC           : integer := 96; -- PIXELS
396 
             VGA_HOR_FRONT_PORCH    : integer := 24; -- PIXELS
397 
             VGA_VER_BACK_PORCH     : integer := 13; -- LINES
398 
             VGA_VER_SYNC           : integer := 1;  -- LINES
399 
             VGA_VER_FRONT_PORCH    : integer := 36  -- LINES
400 
      );
401 
      port(
402 
                -- control register interface
403 
      vdu_clk      : in  std_logic;      -- CPU Clock - 12.5MHz
404 
      vdu_rst      : in  std_logic;
405 
                vdu_cs       : in  std_logic;
406 
                vdu_rw       : in  std_logic;
407 
                vdu_addr     : in  std_logic_vector(2 downto 0);
408 
      vdu_data_in  : in  std_logic_vector(7 downto 0);
409 
      vdu_data_out : out std_logic_vector(7 downto 0);
410 
 
411 
      -- vga port connections
412 
                vga_clk      : in  std_logic;   -- VGA Pixel Clock - 25 MHz
413 
      vga_red_o    : out std_logic;
414 
      vga_green_o  : out std_logic;
415 
      vga_blue_o   : out std_logic;
416 
      vga_hsync_o  : out std_logic;
417 
      vga_vsync_o  : out std_logic
418 
   );
419 
end component;
420 
 
421 
----------------------------------------
422 
--
423 
-- Seven Segment Display driver
424 
--
425 
----------------------------------------
426 
 
427 
component seven_segment is
428 
        port (
429 
          clk         : in  std_logic;
430 
     rst         : in  std_logic;
431 
     cs          : in  std_logic;
432 
     rw          : in  std_logic;
433 
     addr        : in  std_logic_vector(1 downto 0);
434 
     data_in     : in  std_logic_vector(7 downto 0);
435 
          data_out    : out std_logic_vector(7 downto 0);
436 
          segments    : out std_logic_vector(7 downto 0);
437 
          digits             : out std_logic_vector(3 downto 0)
438 
        );
439 
end component;
440 
 
441 
component BUFG
442 
  port (
443 
    i            : in  std_logic;
444 
    o            : out std_logic
445 
  );
446 
end component;
447 
 
448 
begin
449 
  -----------------------------------------------------------------------------
450 
  -- Instantiation of internal components
451 
  -----------------------------------------------------------------------------
452 
 
453 
my_cpu : cpu09  port map (
454 
         clk         => cpu_clk,
455 
    rst       => cpu_reset,
456 
    rw       => cpu_rw,
457 
    vma       => cpu_vma,
458 
    address   => cpu_addr(15 downto 0),
459 
    data_in   => cpu_data_in,
460 
         data_out  => cpu_data_out,
461 
         halt      => cpu_halt,
462 
         hold      => cpu_hold,
463 
         irq       => cpu_irq,
464 
         nmi       => cpu_nmi,
465 
         firq      => cpu_firq
466 
    );
467 
 
468 
my_rom : mon_rom port map (
469 
    clk       => cpu_clk,
470 
    rst       => cpu_reset,
471 
         cs        => rom_cs,
472 
         rw        => '1',
473 
    addr      => cpu_addr(11 downto 0),
474 
    rdata     => rom_data_out,
475 
    wdata     => cpu_data_out
476 
    );
477 
 
478 
my_flex : flex_ram port map (
479 
    clk       => cpu_clk,
480 
    rst       => cpu_reset,
481 
         cs        => flex_cs,
482 
         rw        => cpu_rw,
483 
    addr      => cpu_addr(12 downto 0),
484 
    rdata     => flex_data_out,
485 
    wdata     => cpu_data_out
486 
    );
487 
 
488 
my_dat : dat_ram port map (
489 
    clk       => cpu_clk,
490 
         rst       => cpu_reset,
491 
         cs        => dat_cs,
492 
         rw        => cpu_rw,
493 
         addr_hi   => cpu_addr(15 downto 12),
494 
         addr_lo   => cpu_addr(3 downto 0),
495 
    data_in   => cpu_data_out,
496 
         data_out  => dat_addr(7 downto 0)
497 
         );
498 
 
499 
my_acia  : ACIA_6850 port map (
500 
         clk         => cpu_clk,
501 
         rst       => cpu_reset,
502 
    cs        => acia_cs,
503 
         rw        => cpu_rw,
504 
    irq       => acia_irq,
505 
    Addr      => cpu_addr(0),
506 
         Datain    => cpu_data_out,
507 
         DataOut   => acia_data_out,
508 
         RxC       => acia_clk,
509 
         TxC       => acia_clk,
510 
         RxD       => acia_rxd,
511 
         TxD       => acia_txd,
512 
         DCD_n     => acia_dcd_n,
513 
         CTS_n     => acia_cts_n,
514 
         RTS_n     => open
515 
         );
516 
 
517 
 
518 
----------------------------------------
519 
--
520 
-- ACIA Clock
521 
--
522 
----------------------------------------
523 
my_ACIA_Clock : ACIA_Clock
524 
  generic map(
525 
    SYS_Clock_Frequency  => SYS_Clock_Frequency,
526 
         ACIA_Clock_Frequency => ACIA_Clock_Frequency
527 
  )
528 
  port map(
529 
    clk        => sys_clk,
530 
    acia_clk   => acia_clk
531 
  );
532 
 
533 
 
534 
----------------------------------------
535 
--
536 
-- PS/2 Keyboard Interface
537 
--
538 
----------------------------------------
539 
my_keyboard : keyboard
540 
   generic map (
541 
        KBD_Clock_Frequency => CPU_Clock_frequency
542 
        )
543 
   port map(
544 
        clk          => cpu_clk,
545 
        rst          => cpu_reset,
546 
        cs           => keyboard_cs,
547 
        rw           => cpu_rw,
548 
        addr         => cpu_addr(0),
549 
        data_in      => cpu_data_out(7 downto 0),
550 
        data_out     => keyboard_data_out(7 downto 0),
551 
        irq          => keyboard_irq,
552 
        kbd_clk      => ps2c,
553 
        kbd_data     => ps2d
554 
        );
555 
 
556 
----------------------------------------
557 
--
558 
-- Video Display Unit instantiation
559 
--
560 
----------------------------------------
561 
my_vdu : vdu8
562 
  generic map(
563 
      VDU_CLOCK_FREQUENCY    => CPU_Clock_Frequency, -- HZ
564 
      VGA_CLOCK_FREQUENCY    => VGA_Clock_Frequency, -- HZ
565 
           VGA_HOR_CHARS          => 80, -- CHARACTERS
566 
           VGA_VER_CHARS          => 25, -- CHARACTERS
567 
           VGA_PIXELS_PER_CHAR    => 8,  -- PIXELS
568 
           VGA_LINES_PER_CHAR     => 16, -- LINES
569 
           VGA_HOR_BACK_PORCH     => 40, -- PIXELS
570 
           VGA_HOR_SYNC           => 96, -- PIXELS
571 
           VGA_HOR_FRONT_PORCH    => 24, -- PIXELS
572 
           VGA_VER_BACK_PORCH     => 13, -- LINES
573 
           VGA_VER_SYNC           => 1,  -- LINES
574 
           VGA_VER_FRONT_PORCH    => 36  -- LINES
575 
  )
576 
  port map(
577 
 
578 
                -- Control Registers
579 
                vdu_clk       => cpu_clk,                                        -- 12.5 MHz System Clock in
580 
      vdu_rst       => cpu_reset,
581 
                vdu_cs        => vdu_cs,
582 
                vdu_rw        => cpu_rw,
583 
                vdu_addr      => cpu_addr(2 downto 0),
584 
                vdu_data_in   => cpu_data_out,
585 
                vdu_data_out  => vdu_data_out,
586 
 
587 
      -- vga port connections
588 
      vga_clk       => vga_clk,                                  -- 25 MHz VDU pixel clock
589 
      vga_red_o     => red,
590 
      vga_green_o   => green,
591 
      vga_blue_o    => blue,
592 
      vga_hsync_o   => hs,
593 
      vga_vsync_o   => vs
594 
   );
595 
 
596 
 
597 
----------------------------------------
598 
--
599 
-- Seven Segment Display instantiation
600 
--
601 
----------------------------------------
602 
 
603 
my_seg : seven_segment port map (
604 
    clk        => cpu_clk,
605 
         rst        => cpu_reset,
606 
         cs         => seg_cs,
607 
         rw         => cpu_rw,
608 
         addr       => cpu_addr(1 downto 0),
609 
    data_in    => cpu_data_out,
610 
         data_out   => seg_data_out,
611 
         segments   => segments,
612 
         digits     => digits
613 
         );
614 
 
615 
 
616 
vga_clk_buffer : BUFG port map(
617 
    i => clk_count,
618 
         o => vga_clk
619 
    );
620 
 
621 
cpu_clk_buffer : BUFG port map(
622 
    i => clk_count,
623 
         o => cpu_clk
624 
    );
625 
 
626 
--
627 
-- Clock divider
628 
-- Assumes 50 MHz system clock
629 
-- 25MHz pixel clock
630 
-- 25MHz CPU clock
631 
--
632 
sys09_clock : process( sys_clk, clk_count )
633 
begin
634 
        if sys_clk'event and sys_clk='1' then
635 
           clk_count <= not clk_count;
636 
   end if;
637 
end process;
638 
 
639 
----------------------------------------------------------------------
640 
--
641 
-- Process to decode memory map
642 
--
643 
----------------------------------------------------------------------
644 
 
645 
mem_decode: process( cpu_addr, cpu_rw, cpu_vma,
646 
                                              dat_cs, dat_addr,
647 
                                              rom_data_out,
648 
                                                   acia_data_out,
649 
                                                        keyboard_data_out,
650 
                                                        vdu_data_out,
651 
                                                        seg_data_out,
652 
                                                        leds_data_out,
653 
                                                        flex_data_out,
654 
                                                        ram_data_out
655 
                                                        )
656 
begin
657 
      cpu_data_in <= (others=>'0');
658 
      dat_cs      <= '0';
659 
      rom_cs      <= '0';
660 
      acia_cs     <= '0';
661 
      keyboard_cs <= '0';
662 
      vdu_cs      <= '0';
663 
      seg_cs      <= '0';
664 
      leds_cs     <= '0';
665 
      flex_cs     <= '0';
666 
      ram_cs      <= '0';
667 
--           timer_cs    <= '0';
668 
--      trap_cs     <= '0';
669 
--           pb_cs       <= '0';
670 
--      ide_cs      <= '0';
671 
--      ether_cs    <= '0';
672 
--           slot1_cs    <= '0';
673 
--      slot2_cs    <= '0';
674 
 
675 
      if cpu_addr( 15 downto 8 ) = "11111111" then
676 
             cpu_data_in <= rom_data_out;
677 
        dat_cs      <= cpu_vma;              -- write DAT
678 
        rom_cs      <= cpu_vma;              -- read  ROM
679 
           --
680 
                -- Sys09Bug Monitor ROM $F000 - $FFFF
681 
                --
682 
           elsif dat_addr(3 downto 0) = "1111" then -- $XF000 - $XFFFF
683 
           --
684 
                -- Monitor ROM $F000 - $FFFF
685 
                --
686 
        cpu_data_in <= rom_data_out;
687 
        rom_cs      <= cpu_vma;          -- read  ROM
688 
 
689 
      --
690 
                -- IO Devices $E000 - $EFFF
691 
                --
692 
                elsif dat_addr(3 downto 0) = "1110" then -- $XE000 - $XEFFF
693 
                        case cpu_addr(11 downto 8) is
694 
                        --
695 
                        -- SWTPC peripherals from $E000 to $E0FF
696 
                        --
697 
                        when "0000" =>
698 
                     case cpu_addr(7 downto 4) is
699 
                          --
700 
                          -- ACIA ($E000 - $E00F)
701 
                          --
702 
                          when "0000" =>
703 
                       cpu_data_in <= acia_data_out;
704 
                            acia_cs     <= cpu_vma;
705 
 
706 
                --
707 
                          -- Reserved - FD1771 FDC ($E010 - $E01F) (SWTPC)
708 
           --
709 
 
710 
                          --
711 
           -- Keyboard port ($E020 - $E02F)
712 
                          --
713 
                          when "0010" =>
714 
             cpu_data_in <= keyboard_data_out;
715 
                            keyboard_cs <= cpu_vma;
716 
 
717 
           --
718 
           -- VDU port ($E030 - $E03F)
719 
                          --
720 
                          when "0011" =>
721 
             cpu_data_in <= vdu_data_out;
722 
                            vdu_cs      <= cpu_vma;
723 
 
724 
           --
725 
                          -- Reserved - SWTPc MP-T ($E040 - $E04F)
726 
                          --
727 
 
728 
           --
729 
           -- Reserved - Timer ($E050 - $E05F) (B5-X300)
730 
                          --
731 
 
732 
           --
733 
           -- Reserved - Bus Trap Logic ($E060 - $E06F) (B5-X300)
734 
                          --
735 
 
736 
           --
737 
           -- Reserved - I/O port ($E070 - $E07F) (B5-X300)
738 
                          --
739 
 
740 
                          --
741 
                          -- Reserved - PTM 6840 ($E080 - $E08F) (SWTPC)
742 
                          --
743 
 
744 
                          --
745 
                          -- Reserved - PIA Timer ($E090 - $E09F) (SWTPC)
746 
                          --
747 
 
748 
           --
749 
                          -- Read Switched port ($E0A0 - $E0AF)
750 
                          -- Write LEDS
751 
                          --
752 
                          when "1010" =>
753 
             cpu_data_in <= leds_data_out;
754 
                            leds_cs     <= cpu_vma;
755 
 
756 
           --
757 
           -- 7 segment display port ($E0B0 - $E0BF)
758 
                          --
759 
                          when "1011" =>
760 
             cpu_data_in <= seg_data_out;
761 
                            seg_cs      <= cpu_vma;
762 
 
763 
 
764 
                          when others => -- $EXC0 to $EXFF
765 
                            null;
766 
                     end case;
767 
                        --
768 
                        -- XST-3.0 Peripheral Bus goes here
769 
                        --      $E100 to $E1FF
770 
                        --      Four devices
771 
                        -- IDE, Ethernet, Slot1, Slot2
772 
                        --
773 
--                      when "0001" =>
774 
--                        cpu_data_in <= pb_data_out;
775 
--                        pb_cs       <= cpu_vma;
776 
--                   case cpu_addr(7 downto 6) is
777 
                          --
778 
                          -- IDE Interface $E100 to $E13F
779 
                          --
780 
--                        when "00" =>
781 
--                          ide_cs   <= cpu_vma;
782 
                          --
783 
                          -- Ethernet Interface $E140 to $E17F
784 
                          --
785 
--                        when "01" =>
786 
--                          ether_cs <= cpu_vma;
787 
                          --
788 
                          -- Slot 1 Interface $E180 to $E1BF
789 
                          --
790 
--                        when "10" =>
791 
--                          slot1_cs <= cpu_vma;
792 
                          --
793 
                          -- Slot 2 Interface $E1C0 to $E1FF
794 
                          --
795 
--                        when "11" =>
796 
--                          slot2_cs <= cpu_vma;
797 
           --
798 
                          -- Nothing else
799 
                          --
800 
--         when others =>
801 
--           null;
802 
--         end case;
803 
         --
804 
                        --      $E200 to $EFFF reserved for future use
805 
                        --
806 
                when others =>
807 
                          null;
808 
         end case;
809 
           --
810 
                -- FLEX RAM $0C000 - $0DFFF
811 
                --
812 
                elsif dat_addr(7 downto 1) = "0000110" then -- $0C000 - $0DFFF
813 
        cpu_data_in <= flex_data_out;
814 
        flex_cs     <= cpu_vma;
815 
                --
816 
                -- Everything else is RAM
817 
                --
818 
                else
819 
                  cpu_data_in <= ram_data_out;
820 
                  ram_cs      <= cpu_vma;
821 
    end if;
822 
end process;
823 
 
824 
 
825 
--
826 
-- 1M byte SRAM Control
827 
-- Processes to read and write memory based on bus signals
828 
--
829 
ram_process: process( cpu_reset, sys_clk,
830 
                      cpu_addr, cpu_rw, cpu_vma, cpu_data_out,
831 
                                               dat_addr, ram_cs,
832 
                      ram1_ce, ram1_ub, ram1_lb, ram1_data,
833 
                      ram2_ce, ram2_ub, ram2_lb, ram2_data,
834 
                                                         ram_we, ram_oe )
835 
begin
836 
    --
837 
    -- ram_hold signal helps
838 
    --
839 
    if( cpu_reset = '1' ) then
840 
           ram_we   <= '0';
841 
           ram_oe   <= '0';
842 
    --
843 
         -- Clock Hold on rising edge
844 
         --
845 
    elsif( sys_clk'event and sys_clk='1' ) then
846 
           if (ram_cs = '1') and (ram_we = '0') and (ram_oe = '0') then
847 
             ram_we   <= not cpu_rw;
848 
             ram_oe   <=     cpu_rw;
849 
      else
850 
             ram_we   <= '0';
851 
             ram_oe   <= '0';
852 
      end if;
853 
    end if;
854 
 
855 
         ram_wen  <= not ram_we;
856 
         ram_oen  <= not ram_oe;
857 
 
858 
    ram1_ce   <= ram_cs and (not cpu_addr(1));
859 
    ram1_ub   <= not cpu_addr(0);
860 
    ram1_lb   <= cpu_addr(0);
861 
    ram1_cen  <= not ram1_ce;
862 
    ram1_ubn  <= not ram1_ub;
863 
    ram1_lbn  <= not ram1_lb;
864 
 
865 
    ram2_ce   <= ram_cs and cpu_addr(1);
866 
    ram2_ub   <= not cpu_addr(0);
867 
    ram2_lb   <= cpu_addr(0);
868 
    ram2_cen  <= not ram2_ce;
869 
    ram2_ubn  <= not ram2_ub;
870 
    ram2_lbn  <= not ram2_lb;
871 
 
872 
         ram_addr(17 downto 10) <= dat_addr(7 downto 0);
873 
         ram_addr(9 downto 0) <= cpu_addr(11 downto 2);
874 
 
875 
    if ram_we = '1' and ram1_ce = '1' and ram1_lb = '1' then
876 
                ram1_data(7 downto 0) <= cpu_data_out;
877 
         else
878 
      ram1_data(7 downto 0)  <= "ZZZZZZZZ";
879 
         end if;
880 
 
881 
    if ram_we = '1' and ram1_ce = '1' and ram1_ub = '1' then
882 
                ram1_data(15 downto 8) <= cpu_data_out;
883 
         else
884 
      ram1_data(15 downto 8)  <= "ZZZZZZZZ";
885 
         end if;
886 
 
887 
    if ram_we = '1' and ram2_ce = '1' and ram2_lb = '1' then
888 
                ram2_data(7 downto 0) <= cpu_data_out;
889 
         else
890 
      ram2_data(7 downto 0)  <= "ZZZZZZZZ";
891 
         end if;
892 
 
893 
    if ram_we = '1' and ram2_ce = '1' and ram2_ub = '1' then
894 
                ram2_data(15 downto 8) <= cpu_data_out;
895 
         else
896 
      ram2_data(15 downto 8)  <= "ZZZZZZZZ";
897 
         end if;
898 
 
899 
         case cpu_addr(1 downto 0) is
900 
         when "00" =>
901 
      ram_data_out <= ram1_data(15 downto 8);
902 
         when "01" =>
903 
      ram_data_out <= ram1_data(7 downto 0);
904 
         when "10" =>
905 
      ram_data_out <= ram2_data(15 downto 8);
906 
    when others =>
907 
      ram_data_out <= ram2_data(7 downto 0);
908 
    end case;
909 
end process;
910 
 
911 
--
912 
-- LEDS output register
913 
--
914 
leds_output : process( cpu_clk, cpu_reset, switches )
915 
begin
916 
        if cpu_reset = '1' then
917 
                leds <= "00000000";
918 
        elsif cpu_clk'event and cpu_clk='0' then
919 
                if      leds_cs = '1' and cpu_rw = '0' then
920 
                        leds <= cpu_data_out;
921 
                end if;
922 
        end if;
923 
        leds_data_out <= switches;
924 
end process;
925 
 
926 
--
927 
-- Interrupts and other bus control signals
928 
--
929 
interrupts : process(   rst_sw,
930 
                                                                acia_irq,
931 
                                                                keyboard_irq,
932 
                                                                nmi_sw
933 
                                                         )
934 
begin
935 
   if sys_clk'event and sys_clk = '1' then
936 
          cpu_reset  <= rst_sw; -- CPU reset is active high
937 
   end if;
938 
        cpu_firq   <= keyboard_irq;
939 
        cpu_nmi    <= nmi_sw;
940 
        cpu_irq    <= acia_irq;
941 
        cpu_halt   <= '0';
942 
        cpu_hold   <= '0';
943 
end process;
944 
 
945 
--
946 
-- ACIA pin assignments
947 
--
948 
acia_assignments : process( rxd, acia_txd )
949 
begin
950 
        acia_dcd_n <= '0';
951 
        acia_cts_n <= '0';
952 
        acia_rxd   <= rxd;
953 
        txd        <= acia_txd;
954 
end process;
955 
 
956 
 
957 
end my_computer; --===================== End of architecture =======================--
958 
 

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